The Sleeper Stretch is a common exercise used to improve internal rotation of the shoulder and stretch the posterior capsule. Lie on your side on a firm surface with the shoulder you want to stretch underneath you. Bend your arm at a 90-degree angle with the elbow in line with the shoulder. Use your other hand to gently push your forearm down towards the floor. Stop when you feel a stretch in the back of your shoulder and hold for 30 seconds. Tip: Do not bend your wrist or press down on your wrist; apply pressure to the forearm instead.